Allozyme variation in two populations of the Mopane worm, Imbrasia belina (Saturniidae), and the effect of developmental stage and staggered generations

Imbrasia belina is utilised as a food item by certain ethnic groups of southern Africa, but little is known of the genetic structure of this resource. The aims of this study were to determine whether the limited flight ability of moths has an effect on gene flow between two geographically distant I. belina populations, whether there are gene expression differences between moths, worms and pupae and whether staggered generations have different genotypic expressions. Gene products of 19 protein-coding loci from moths collected at two locations, one of which included two staggered generations, were analysed by horizontal starch gel electrophoresis. High levels of polymorphism (42% and 47%) and heterozygosity (0.182 to 0.210) were present in all groups. There were developmental constraints on the expression of the phosphoglucomutase enzyme coding locus, and only allozyme and not isozyme differences between individuals from the various developmental stages were found at other loci. Although the groups displayed a large amount of variation, little differentiation and a large amount of gene flow were observed between them. Results indicate that the genetic diversity of I. belina populations is relatively high. The February-hatching Messina group is recommended for commercial utilisation due to the large amount of genetic variation in this population.